Light guide plates and process for producing the same

ABSTRACT

Disclosed are an optical waveguide that comprises (A) a copolyester carbonate having aliphatic segment(s), and a method for producing it; and an optical waveguide made from a polycarbonate resin composition that comprises (A) a copolyester carbonate having aliphatic segment(s) and (B) an aromatic polycarbonate, and a method for producing it. The polycarbonate resin composition for the optical waveguide has the advantages of high mechanical strength and improved flowability.

TECHNICAL FIELD

The present invention relates to a light guide plate (an opticalwaveguide) and to a method for producing it. More precisely, theinvention relates to an optical waveguide for backlight units, forexample, for automobile meter panels and tail lamps, in particular tothat having a microprism structure that serves as a light-scatteringlayer, and relates to a method for producing such an optical waveguide.

BACKGROUND ART

Ordinary backlight units for liquid-crystal image displays and those forvarious guide lights generally have a built-in surface light source thatemits light uniformly. The surface light source is made of a transparenttabular molding. This receives the light from a main light source,cathode ray tube (fluorescent lamp) combined with it, and emits lightfrom its surface, and this is referred to as an optical waveguide.Specifically, the light from the main light source enters the opticalwaveguide through its side surface, and a part of it runs inside theoptical waveguide and scatters on the light-scattering layer disposed onthe back surface of the optical waveguide to give scattered light, and,as a result, the entire surface of the optical waveguide emits lightuniformly.

For forming the light-scattering layer, heretofore, a dot pattern isprinted on the back surface of a plate to be an optical waveguide, orthe back surface thereof is machined with a conical drill. However, suchmethods require a high-level technique. Therefore, the recent tendencyin the art is toward a method of transferring a microprism structureonto a plate to be an optical waveguide.

The material of such an optical waveguide must satisfy the requirementof high-level complete light transmittance, for which, therefore,generally used is acrylic resin (PMMA) However, acrylic resin does nothave good heat resistance, high mechanical strength and good flameretardancy, and is therefore unsuitable for lighting units of, forexample, displays, tail lamps and winkers for automobiles. As opposed tothis, polycarbonate resin is being used for that purpose, as having goodheat resistance, high mechanical strength and good flame retardancy.However, ordinary polycarbonate resin is poorly flowable, and istherefore problematic in that the transferability of a microprismstructure onto a plate of the resin is not good. For improving thetransferability of such polycarbonate resin, known is a method oflowering the molecular weight of the resin. However, the reduction inthe molecular weight of the resin detracts from the mechanical strengththereof. Accordingly, for the material of an optical waveguide, desiredis polycarbonate resin having good flowability and high mechanicalstrength. The present invention has been made in consideration of thesituation mentioned above, and is to provide an optical waveguide madefrom a polycarbonate resin composition having improved flowability, andto provide a method for producing it.

DISCLOSURE OF THE INVENTION

We, the present inventors have assiduously studied, and, as a result,have found that a polycarbonate resin composition comprising acopolyester carbonate having aliphatic segment(s) and an aromaticpolycarbonate meets the object of the invention mentioned above. On thebasis of this finding, we have completed the present invention.

Specifically, the invention is summarized as follows:

1. An optical waveguide which comprises (A) a copolyester carbonatehaving aliphatic segment(s).

2. An optical waveguide made from a polycarbonate resin composition thatcomprises (A) a copolyester carbonate having aliphatic segment (s), andat least one resin selected from (B) an aromatic polycarbonate and (C)an acrylic resin, in which the amount of (B) is at most up to 90 partsby weight relative to 100 parts by weight of (A), and the amount of (C)falls between 0.01 and 1.0 part by weight relative to 100 parts byweight of (A).

3. The optical waveguide of above 1 or 2, wherein the aliphatic segmentin the component (A) is derived from a polymethylene-dicarboxylic acid,and the ratio of the polymethylene-dicarboxylic acid falls between 1 and30 mol % of the main monomer (diphenol) that constitutes thepolycarbonate resin composition.

4. An optical waveguide which comprises an aromatic polycarbonate resinterminated with a substituted phenoxy group of a general formula:

in which R¹ represents an alkyl group having from 10 to 30 carbon atoms,or a branched alkyl group having from 10 to 30 carbon atoms,or a formula:

or a formula

5. The optical waveguide of above 4, which contains from 0.01 to 1.0part by weight of an acrylic resin relative to 100 parts by weight ofthe aromatic polycarbonate resin therein.

6. The optical waveguide of any of above 1 to 5, which is made of atabular molding and has, on its face or back, a microprism structurethat serves as a light-scattering layer.

7. The optical waveguide of above 6, wherein the microprism structure isa regular tetrahedral structure.

8. The optical waveguide of above 7, wherein the regular tetrahedralstructure has a height falling between 10 and 300 μm.

9. A method for producing the optical waveguide of any of above 6 to 8,in which, when a tabular molding for it is injection-molded, amicroprism structure that serves as a light-scattering layer istransferred onto its face or back with a stamper.

BEST MODES OF CARRYING OUT THE INVENTION

The invention is described in detail hereinunder.

For the optical waveguide of the invention, used is a polycarbonateresin composition that comprises (A) a copolyester carbonate havingaliphatic segment(s) and (B) an aromatic polycarbonate.

The copolyester carbonate having aliphatic segment(s) for the component(A) of the invention (this is hereinafter referred to as BPA-PMDCcopolymer) comprises, for example, an aromatic polycarbonate moiety anda polyester moiety derived from a diphenol and apolymethylene-dicarboxylic acid. Preferably, it is a copolymer having,in the molecule, an aromatic polycarbonate moiety that comprisesstructural units of the following structural formula (1), and apolyester moiety that comprises structural units of the followingstructural formula (2):

wherein R¹ and R² each represent an alkyl group having from 1 to 6carbon atoms, or a phenyl group, and they may be the same or different;Z represents a single bond, an alkylene group having from 1 to 20 carbonatoms, an alkylidene group having from 1 to 20 carbon atoms, acycloalkylene group having from 5 to 20 carbon atoms, a cycloalkylidenegroup having from 5 to 20 carbon atoms, or a bond of —SO₂—, —SO—, —S—,—O— or —CO—, and it is preferably an isopropylidene group;a and b each indicate an integer falling between 0 and 4, and arepreferably 0; and n indicates an integer falling between 8 and 20.

The BPA-PMDC copolymer is produced, for example, through interfacialpolycondensation of a polycarbonate oligomer (hereinafter referred to asPC oligomer) having been previously prepared to constitute the aromaticpolycarbonate moiety of the copolymer with a polymethylene-dicarboxylicacid in such a manner that the two are dissolved in a solvent such asmethylene chloride, chlorobenzene or chloroform, then an aqueous causticalkali solution of a diphenol is added thereto, and they areinterfacially polycondensed in the presence of a tertiary amine (e.g.,triethylamine) or a quaternary ammonium salt (e.g.,trimethylbenzylammonium chloride) serving as a catalyst and in thepresence of a terminator.

The terminator may be any and every one generally used in polycarbonateproduction. Concretely, for example, it includes phenol, p-cresol,p-tert-butylphenol, and tert-octylphenol. Preferred for it is amonophenol such as p-tert-octylphenol, p-cumylphenol, p-nonylphenol,p-tert-amylphenol. Also usable for the terminator are phenols of thefollowing general formula:

wherein R¹ represents an alkyl group having from 10 to 30 carbon atoms,preferably an alkyl group having from 10 to 20 carbon atoms. If thenumber of carbon atoms constituting R¹ in this is smaller than 10, it isundesirable since the flowability of the aromatic polycarbonate resinproduced in the presence of the terminator of the type will be low; butif larger than 30, it is also undesirable since the heat resistancethereof will gradually lower. The alkyl group in this may be linear orbranched. Of the phenols, especially preferred are p-alkylphenols. Thecopolymer may be incompletely terminated with the terminator, stillhaving a hydroxyl residue of the diphenol that remains at its ends, andits terminal fraction may be at least 60%.

The PC oligomer may be readily prepared, for example, by reacting adiphenol of the following general formula (3):

in which R¹, R², Z, a and b have the same meanings as above, with acarbonate precursor such as phosgene or a carbonate compound, in asolvent such as methylene chloride. Concretely, for example, thediphenol is reacted with a carbonate precursor such as phosgene in asolvent such as methylene chloride, or it is transesterified with acarbonate precursor such as diphenyl carbonate.

For the diphenol of formula (3), especially preferred is2,2-bis(4-hydroxyphenyl)propane (generally referred to as bisphenol A).Except bisphenol A, the diphenol includes, for example,bis(hydroxyaryl)alkanes such as bis(4-hydroxyphenyl)methane,1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)butane,2,2-bis(4-hydroxyphenyl)octane,2,2-bis(4-hydroxy-1-methylphenyl)propane,1,1-bis(4-hydroxy-tert-butylphenyl)propane,2,2-bis(4-hydroxy-3-bromophenyl)propane,2,2-bis(4-hydroxy-3,5-tetramethylphenyl)propane,2,2-bis(4-hydroxy-3-chlorophenyl)propane,2,2-bis(4-hydroxy-3,5-tetrachlorophenyl)propane,2,2-bis(4-hydroxy-3,5-tetrabromophenyl)propane;bis(hydroxyaryl)arylalkanes such as2,2-bis(4-hydroxyphenyl)phenylmethane,bis(4-hydroxyphenyl)naphthylmethane; bis(hydroxyaryl)cycloalkanes suchas 1,1-bis(4-hydroxyphenyl)cyclopentane,1,1-bis(4-hydroxyphenyl)cyclohexane,1,1-bis(4-hydroxyphenyl)-3,5,5-trimethylcyclohexane; dihydroxyarylethers such as 4,4′-dihydroxyphenyl ether,4,4′-dihydroxy-3,3′-dimethylphenyl ether; dihydroxydiaryl sulfides suchas 4,4′-dihydroxydiphenyl sulfide, 4,4′-dihydroxy-3,3′-dimethyldiphenylsulfide; dihydroxydiaryl sulfoxides such as 4,4′-dihydroxydiphenylsulfoxide, 4,4′-dihydroxy-3, 3′-dimethyldiphenyl sulfoxide;dihydroxydiaryl sulfones such as 4,4′-dihydroxydiphenyl sulfone,4,4′-dihydroxy-3,3′-dimethyldiphenyl sulfone; and dihydroxydiphenylssuch as 4,4′-dihydroxydiphenyl. One or more of these diphenols may beused herein either singly or as combined.

The carbonate compound includes, for example, diaryl carbonates such asdiphenyl carbonate; and dialkyl carbonates such as dimethyl carbonate,diethyl carbonate.

The PC oligomer to be used in producing the PC-PMDC copolymer for use inthe invention may be a homopolymer of one type of the diphenol mentionedabove, or a copolymer of two or more different types thereof. Inaddition, it may also be a thermoplastic random branched polycarbonateobtained from a polyfunctional aromatic compound and the diphenol. Forit, the branching agent (polyfunctional aromatic compound) includes, forexample, 1,1,1-tris(4-hydroxyphenyl)ethane, α, α′,α″-tris(4-hydroxyphenyl)-1,3,5-triisopropylbenzene,1-[α-methyl-α-(4′-hydroxyphenyl)ethyl]-4-[α′, α-4-[α′,α′-bis(4″-hydroxyphenyl)ethyl]benzene, phloroglucine, trimellitic acid,isatin-bis(o-cresol).

Preferably, the number of methylene units in thepolymethylene-dicarboxylic acid falls between 8 and 20. Concretely, theacid includes, for example, octane-dicarboxylic acid,decane-dicarboxylic acid, and dodecanedicarboxylic acid, of whichdecane-dicarboxylic acid is more preferred.

The component (A) can be produced in the manner mentioned above, but itsproduction generally gives an aromatic polycarbonate as the sideproduct. Preferably, the viscosity-average molecular weight of thecomponent (A) falls between 10,000 and 40,000, more preferably between12,000 and 30,000.

On the other hand, the viscosity-average molecular weight of thecomponent (B), aromatic polycarbonate preferably falls between 10,000and 40,000, more preferably between 12,000 and 30,000. The aromaticpolycarbonate is not specifically defined, and it can be readilyproduced through reaction of a diphenol with phosgene or a carbonatecompound.

Concretely, for example, in a solvent such as methylene chloride in thepresence of a terminator such as triethylamine, a diphenol is reactedwith a carbonate precursor such as phosgene, or it is transesterifiedwith a carbonate precursor such as diphenyl carbonate.

The diphenol may be the same as those of formula (3) mentioned above, ormay be different from them. The polycarbonate may be a homopolymer ofone type of the diphenol, or a copolymer of two or more different typesthereof. In addition, it may also be a thermoplastic random branchedpolycarbonate obtained from a polyfunctional aromatic compound and thediphenol.

Examples of the carbonate compound are diaryl carbonates such asdiphenyl carbonate, and dialkyl carbonates such as dimethyl carbonate,diethyl carbonate.

Like in the above, the terminator may be any and every one generallyused in ordinary polycarbonate production.

The viscosity-average molecular weight of the polycarbonate resincomposition comprising the components (A) and (B) for the opticalwaveguide of the invention preferably falls between 10,000 and 40,000,more preferably between 12,000 and 25,000, even more preferably between14,000 and 19,000. If its molecular weight is too small, the mechanicalstrength of the resin composition of the invention will be often low;but if too large, the flowability thereof will be often poor.Preferably, the amount of the polymethylene-dicarboxylic acid to be usedherein falls between 1 and 30 mol %, more preferably between 2 and 20mol %, even more preferably between 5 and 10 mol % of the main monomer(diphenol) that constitutes the polycarbonate resin compositioncomprising the components (A) and (B). If the amount of thepolymethylene-dicarboxylic acid is too small, the flowability of thepolycarbonate resin composition could not be improved; but if too large,the heat resistance thereof will be low.

For improving its photoconductivity, the polycarbonate resin compositionof the invention preferably contains from 0.01 to 1.0 part by weight,relative to 100 parts by weight of the composition, of an acrylic resin(C). If the acrylic resin content of the composition is smaller than0.01 parts by weight, the photoconductivity of the composition could notbe well improved; but if larger than 1.0 part by weight, thephotoconductivity of the composition will be rather lowered. Morepreferably, the acrylic resin content of the composition falls between0.05 and 0.5 parts by weight.

The acrylic resin (C) is a polymer having a repetitive monomer units ofany of acrylic acid, acrylates, acrylonitrile, and their derivatives. Itmay be a homopolymer or a copolymer with any of styrene, butadiene andthe like. Concretely, it includes, for example, polyacrylic acid,polymethyl methacrylate (PMMA), polyacrylonitrile, ethylacrylate-2-chloroethyl acrylate copolymer, n-butylacrylate-acrylonitrile copolymer, acrylonitrile-styrene copolymer,acrylonitrile-butadiene copolymer, and acrylonitrile-butadiene-styrenecopolymer. Of those, especially preferred is polymethyl methacrylate(PMMA).

For preventing it from being thermally degraded to yellow in molding,the polycarbonate resin composition of the invention preferably containsa stabilizer. The stabilizer may be a reactive silicone compound (e.g.,organosiloxane) derived from a silicone compound by introducing afunctional group such as methoxy or vinyl group thereinto. In general,the amount of the stabilizer to be in the polycarbonate resincomposition may fall between 0.01 and 3.0 parts by weight, butpreferably between 0.05 and 2.0 parts by weight, relative to 100 partsby weight of the composition.

Not interfering with the object of the invention, the polycarbonateresin composition may further contain any other various additives. Forexample, it may contain any of antioxidants such as hindered phenols,esters, phosphates and amines; UV absorbents such as benzotriazoles andbenzophenones; optical stabilizers such as hindered amines; internallubricants such as aliphatic carboxylates, paraffins, silicone oils andpolyethylene waxes; and any other ordinary flame retardants, flameretardation promoters, mold release agents, and antistatic agents.

Formulating and kneading the constituents components to prepare thecomposition may be effected in any ordinary manner. For example, thecomponents may be mixed by the use of a ribbon blender, a drum tumbler,a Henschel mixer, a Banbury mixer, a single-screw extruder, adouble-screw extruder, a cokneader, or a multi-screw extruder. Thetemperature in the kneading operation may fall generally between 280 and320° C.

The optical waveguide of the invention is made of a tabular molding ofthe polycarbonate resin composition mentioned above, having alight-scattering layer formed on its face or back. For forming thelight-scattering layer, employable is a method of printing a dot patteron the face or the back of the tabular resin molding, or a method ofmachining the tabular resin molding with a conical drill. Apart fromthese, however, preferred is a method of transferring a microprismstructure onto the face or the back of the tabular resin molding.

The microprism structure is not specifically defined, but is preferablya regular tetrahedral structure. Also preferably, its height fallsbetween 10 and 300 μm, more preferably between 20 and 200 μm, even morepreferably between 50 and 100 μm.

The optical waveguide of the invention may be produced, for example, asfollows: When a tabular molding for it is injection-molded, a microprismstructure that serves as a light-scattering layer is transferred ontoits face or back with a stamper. In this method, the light-scatteringlayer may be formed entirely or partially on the face or the back of thetabular resin molding. Preferably, the resin composition isinjection-molded at a cylinder temperature falling between 260 and 330°C. and at a mold temperature falling between 50 and 120° C.

The thickness of the optical waveguide is not specifically defined, forwhich the tabular molding may have a thickness of about 3 mm. The formof the optical waveguide is not also specifically defined, or that is,it is not all the time limited to a tabular form. For example, theoptical waveguide may be in the form of a curved plate having a lenseffect. Anyhow, the form of the optical waveguide may be suitablydetermined, depending on the object and the use thereof. Still anotherexample of the optical waveguide may be so designed that its thicknessis gradually reduced in the direction remoter from the light source forit, or that is, it has a tapered cross section. If desired, the opticalwaveguide may be designed that it is integrated with a separate displaymember disposed in front of its surface emitter.

The invention is described more concretely with reference to thefollowing Production Examples, Working Examples and ComparativeExamples, which, however, are not intended to restrict the scope of theinvention.

PRODUCTION EXAMPLE 1

[Production of Polycarbonate Oligomer]

60 kg of bisphenol A was dissolved in 400 liters of aqueous 5 wt. %sodium hydroxide solution to prepare an aqueous solution of bisphenol Ain sodium hydroxide. Next, while kept at room temperature, the bisphenolA solution was fed into a tubular reactor (inner diameter: 10 mm,length: 10 m) via an orifice plate at a flow rate of 138 liters/hr, withmethylene chloride thereinto at a flow rate of 69 liters/hr. Along withthese, phosgene was also introduced thereinto at a flow rate of 10.7kg/hr. In that condition, these were continuously reacted for 3 hours.The tubular reactor used herein has a double-wall structure, and coolingwater was circulated through the jacket area so that the temperature ofthe reaction liquid at its outlet could be 25° C. The reaction liquid tobe taken out of the reactor was controlled to have a pH of from 10 to11. The thus-obtained reaction liquid was statically kept as such, andthe aqueous phase was separated and removed. The methylene chloridephase (220 liters) was collected, containing a PC oligomer(concentration; 317 g/liter). The degree of polymerization of thepolycarbonate oligomer thus obtained herein falls 2 and 4, and thenormality of its chloroformate concentration is 0.7.

PRODUCTION EXAMPLE 2

[Production of BPA-PMDC Copolymer A]

10 liters of the polycarbonate oligomer obtained in Production Example 1was put into a 50-liter reactor equipped with a stirrer, to which wereadded an aqueous solution of decane-dicarboxylic acid in sodiumhydroxide (decane-dicarboxylic acid 485 g, sodium hydroxide 168 g, water3 liters) and 5.8 ml of triethylamine. These were stirred at 300 rpm atroom temperature for 1 hour, and reacted. Next, the reaction system wasmixed with an aqueous solution of bisphenol A in sodium hydroxide(bisphenol A 534 g, sodium hydroxide 312 g, water 5 liters) and 136 g ofp-cumylphenyl, to which was added 8 liters of methylene chloride. Thesewere stirred at 500 rpm for 1 hour and reacted. After the reaction, 7liters of methylene chloride and 5 liters of water were added to this,and further stirred at 500 rpm for 10 minutes. After stirring it wasstopped, this was statically kept as such, and the organic phase wasseparated from the aqueous phase. The resulting organic phase was washedwith alkali, 5 liters of aqueous 0.03 N sodium hydroxide solution, thenwith acid, 5 liters of 0.2 N hydrochloric acid, and then twice with 5liters of water in that order. Finally, methylene chloride was removedfrom it, and a flaky polymer was thus obtained. The terminal fraction ofthe p-cumylphenoxy group of the polymer was 99.5%; the viscosity-averagemolecular weight of the polymer was 17,000; and the decane-dicarboxylicacid content of the polymer was 8.1 mol % of all the constituentmonomers.

PRODUCTION EXAMPLE 3

[Production of Aromatic Polycarbonate B]

10 liters of the polycarbonate oligomer obtained in Production Example 1was put into a 50-liter reactor equipped with a stirrer, and 95.9 g ofp-tert-butylphenol was dissolved therein. Next, an aqueous sodiumhydroxide solution (sodium hydroxide 53 g, water 1 liter) and 5.8 ml oftriethylamine were added thereto, stirred at 300 rpm for 1 hour, andreacted. Next, the reaction system was mixed with an aqueous solution ofbisphenol A in sodium hydroxide (bisphenol A 720 g, sodium hydroxide 412g, water 5.5 liters), to which was added 8 liters of methylene chloride.These were stirred at 500 rpm for 1 hour and reacted. After thereaction, 7 liters of methylene chloride and 5 liters of water wereadded to this, and further stirred at 500 rpm for 10 minutes. Afterstirring it was stopped, this was statically kept as such, and theorganic phase was separated from the aqueous phase. The resultingorganic phase was washed with 5 liters of an alkali (0.03 N NaOH), 5liters of an acid (0.2 N HCl), and 5 liters of water (two times) in thatorder. Next, methylene chloride was evaporated away, and a flaky polymerwas thus obtained. The terminal fraction of the p-tert-butylphenoxygroup of the polymer was 99.5%; and the viscosity-average molecularweight of the polymer was 17,000.

The viscosity-average molecular weight (Mv) of the BPA-PMDC copolymerand the aromatic polycarbonate resin was obtained as follows: Theviscosity of the polymer in methylene chloride at 20° C. was measuredwith an Ubbelohde's viscometer, from which was derived the intrinsicviscosity [η] thereof. The viscosity-average molecular weight of thepolymer is calculated according to the following formula:[η]=1.23×10⁻⁵ Mv ^(0.83)

EXAMPLES 1 TO 4, AND COMPARATIVE EXAMPLES 1 TO 3

The polymer prepared in each Production Example was mixed with PMMA(Sumitomo Chemical's Sumipec MG5), a stabilizer (Shin-etu Silicone'sKR219, organosiloxane having methoxy and vinyl groups), and anantioxidant (Asahi Denka Industry's PEP36, phosphorus-containingantioxidant) in the ratio indicated in Table 1. The resulting mixturewas molded in a mold cavity of 60×60×3 mm, with a regular tetrahedralmicroprism (height 70 μm) stamper inserted in the cavity. The cylindertemperature was 320° C., and the mold temperature was 115° C. The degreeof microprism transfer on the thus-obtained optical waveguide, and thefalling weight impact strength and the luminosity of the opticalwaveguide are given in Table 2. The methods of measuring the data aredescribed hereinunder.

PRODUCTION EXAMPLE 4

[Production of Terminal-Modified Polycarbonate A1]

10 liters of the polycarbonate oligomer obtained in Production Example 1was put into a 50-liter reactor equipped with a stirrer, and 167 g ofp-dodecylphenyl (from Yuka Skenectady) was dissolved therein. Next, anaqueous sodium hydroxide solution (sodium hydroxide 53 g, water 1 liter)and 5.8 cc of triethylamine were added thereto, stirred at 300 rpm for 1hour, and reacted. Next, the reaction system was mixed with an aqueoussolution of bisphenol A in sodium hydroxide (bisphenol A 720 g, sodiumhydroxide 412 g, water 5.5 liters), to which was added 8 liters ofmethylene chloride. These were stirred at 500 rpm for 1 hour andreacted. After the reaction, 7 liters of methylene chloride and 5 litersof water were added to this, and further stirred at 500 rpm for 10minutes. After stirring it was stopped, this was statically kept assuch, and the organic phase was separated from the aqueous phase. Theresulting organic phase was washed with 5 liters of an alkali (0.03 NNaOH), 5 liters of an acid (0.2 N HCl), and 5 liters of water (twotimes) in that order. Next, methylene chloride was evaporated away, anda flaky polymer was thus obtained. The polymer was dried at 120° C. for48 hours. The terminal fraction of the p-dodecylphenoxy group of thepolymer was 99.5%; and the viscosity-average molecular weight of thepolymer was 17,000.

PRODUCTION EXAMPLE 5

[Production of Terminal-modified Polycarbonate A2]

A flaky polymer was produced in the same manner as in Production Example4, for which, however, used was 95.5 g of p-tert-butylphenyl in place of167 g of p-dodecylphenyl. The terminal fraction of thep-tert-butylphenoxy group of the polymer was 99.5%; and theviscosity-average molecular weight of the polymer was 17,000.

The viscosity-average molecular weight (Mv) of the polycarbonate resinwas obtained as follows: Its viscosity in methylene chloride at 20° C.was measured with an Ubbelohde's viscometer, from which was derived theintrinsic viscosity [η] of the resin. The viscosity-average molecularweight of the resin is calculated according to the following formula:[η]=1.23×10⁻⁵ Mv ^(0.83)

EXAMPLES 5 TO 7, AND COMPARATIVE EXAMPLES 4 TO 6

The flaky polymer prepared in any of Production Examples 4 and 5 wasmixed with PMMA (Sumitomo Chemical's Sumipec MG5), a stabilizer(Shin-etu Silicone's KR219, organosiloxane having methoxy and vinylgroups), and an antioxidant (Asahi Denka Industry's PEP36,phosphorus-containing antioxidant) in the ratio indicated in Table 1.The resulting mixture was molded in a mold cavity of 60×60×3 mm, with aregular tetrahedral microprism (height 70 μm) stamper inserted in thecavity. The cylinder temperature was 320° C., and the mold temperaturewas 115° C. The degree of microprism transfer on the thus-obtainedoptical waveguide, and the falling weight impact strength and theluminosity of the optical waveguide are given in Table 2. The methods ofmeasuring the data are described hereinunder.

PRODUCTION EXAMPLE 6

[Production of Terminal-Modified Polycarbonate A3]

10 liters of the polycarbonate oligomer obtained in Production Example 1was put into a 50-liter reactor equipped with a stirrer, and 155 g ofp-tert-octylphenol was dissolved therein. Next, an aqueous sodiumhydroxide solution (sodium hydroxide 53 g, water 1 liter) and 5.8 cc oftriethylamine were added thereto, stirred at 300 rpm for 1 hour, andreacted. Next, the reaction system was mixed with an aqueous solution ofbisphenol A in sodium hydroxide (bisphenol A 720 g, sodium hydroxide 412g, water 5.5 liters), to which was added 8 liters of methylene chloride.These were stirred at 500 rpm for 1 hour and reacted. After thereaction, 7 liters of methylene chloride and 5 liters of water wereadded to this, and further stirred at 500 rpm for 10 minutes. Afterstirring it was stopped, this was statically kept as such, and theorganic phase was separated from the aqueous phase. The resultingorganic phase was washed with 5 liters of an alkali (0.03 N NaOH), 5liters of an acid (0.2 N HCl), and 5 liters of water (two times) in thatorder. Next, methylene chloride was evaporated away, and a flaky polymerwas thus obtained. The polymer was dried at 120° C. for 48 hours. Theterminal fraction of the p-tert-octylphenoxy group of the polymer was99.5%; and the viscosity-average molecular weight of the polymer was14,900.

PRODUCTION EXAMPLE 7

[Production of Terminal-Modified Polycarbonate A4]

A flaky polymer was produced in the same manner as in Production Example6, for which, however, used was 113 g of p-tert-butylphenol in place of155 g of p-tert-octylphenol. The terminal fraction of thep-tert-butylphenoxy group of the polymer was 99.5%; and theviscosity-average molecular weight of the polymer was 15,000.

PRODUCTION EXAMPLE 8

[Production of Terminal-Modified Polycarbonate A5]

A flaky polymer was produced in the same manner as in Production Example6, for which, however, used was 71 g of phenyl in place of 155 g ofp-tert-octylphenyl. The terminal fraction of the phenoxy group of thepolymer was 99.5%; and the viscosity-average molecular weight of thepolymer was 15,100.

PRODUCTION EXAMPLE 9

[Production of Terminal-modified Polycarbonate A6]

A flaky polymer was produced in the same manner as in Production Example6, for which, however, used was 95.9 g of p-tert-butylphenol in place of155 g of p-tert-octylphenol. The terminal fraction of thep-tert-butylphenoxy group of the polymer was 99.5%; and theviscosity-average molecular weight of the polymer was 17,000.

The viscosity-average molecular weight (Mv) of the polycarbonate resinwas obtained as follows: Its viscosity in methylene chloride at 20° C.was measured with an Ubbelohde's viscometer, from which was derived theintrinsic viscosity [η] of the resin. The viscosity-average molecularweight of the resin is calculated according to the following formula:[η]=1.23×10⁻⁵ Mv ⁰⁸³

PRODUCTION EXAMPLE 10

[Production of Terminal-Modified Polycarbonate A7]

10 liters of the polycarbonate oligomer obtained in Production Example 1was put into a 50-liter reactor equipped with a stirrer, and 155 g ofp-tert-octylphenol was dissolved therein. Next, an aqueous sodiumhydroxide solution (sodium hydroxide 53 g, water 1 liter) and 5.8 ml oftriethylamine were added thereto, stirred at 300 rpm for 1 hour, andreacted. Next, the reaction system was mixed with an aqueous solution ofbisphenol A in sodium hydroxide (bisphenol A 720 g, sodium hydroxide 412g, water 5.5 liters), to which was added 8 liters of methylene chloride.These were stirred at 500 rpm for 1 hour and reacted. After thereaction, 7 liters of methylene chloride and 5 liters of water wereadded to this, and further stirred at 500 rpm for 10 minutes. Afterstirring it was stopped, this was statically kept as such, and theorganic phase was separated from the aqueous phase. The resultingorganic phase was washed with 5 liters of an alkali (0.03 N NaOH), 5liters of an acid (0.2 N HCl), and 5 liters of water (two times) in thatorder. Next, methylene chloride was evaporated away, and a flaky polymerwas thus obtained. The polymer was dried at 120° C. for 48 hours, andthen pelletized through extrusion at 260° C. The viscosity-averagemolecular weight of the polymer was 15,000.

PRODUCTION EXAMPLE 11

[Production of Terminal-Modified Polycarbonate A8]

A flaky polymer was produced in the same manner as in Production Example10, for which, however, used was 71 g of phenol in place of 155 g ofp-tert-octylphenol. The viscosity-average molecular weight of thepolymer was 15,100. Examples 8 to 10, and Comparative Examples 7 to 10:

The flaky polymer prepared in any of Production Examples 6 to 11 wasmixed with PMMA (Sumitomo Chemical's Sumipec MG5), a stabilizer(Shin-etu Silicone's KR219, organosiloxane having methoxy and vinylgroups), and an antioxidant (Asahi Denka Industry's PEP36,phosphorus-containing antioxidant) in the ratio indicated in Table 1.The resulting mixture was molded in a mold cavity of 60×60×3 mm, with aregular tetrahedral microprism (height 70 μm) stamper inserted in thecavity. The cylinder temperature was 320° C., and the mold temperaturewas 115° C. The degree of microprism transfer on the thus-obtainedoptical waveguide, and the falling weight impact strength and theluminosity of the optical waveguide are given in Table 2. The methods ofmeasuring the data are mentioned below.

(1) Degree of Microprism Transfer:

Ten of the regular tetrahedral microprism structures transferred ontothe optical waveguide were selected, and the value of their mean heightwas divided by 70 μm to obtain the degree (%) of microprism transferonto the optical waveguide. The height of each regular tetrahedralmicroprism structure transferred onto the surface of the opticalwaveguide was measured with an Olympus Optics' scanning lasermicroscope.

(2) Falling Weight Impact Strength:

Measured according to ASTMD-3763-86. The falling weight speed was 7m/sec; and the weight was 36.85 N.

(3) Luminosity:

The back (having a microprism structure transferred thereon) and theside of the optical waveguide were covered with a plate (thickness: 3mm) of high-reflectivity material (this is an injection molding ofIdemitsu Petrochemical's Toughlon HR2500), and a ray from a cold cathodetube (Harison Electric's HMBS26E) was applied thereto at the edgeadjacent to the light source. The face of the optical waveguide wascovered with a milky-white acrylic plate (Mitsubishi Rayon's Acrylight432, having a thickness of 2 mm), and the center part of the opticalwaveguide having received the ray in that condition was measured with aluminometer, Minolta's LS-100.

TABLE 1 Polycarbonate Amount of Resin PMMA Stabilizer AntioxidantPolymethylene- Amount amount amount amount dicarboxylic Acid(*1) Type(wt. pts.) (wt. pts.) (wt. pts.) (wt. pts.) mol % Example 1 A 100 0 00.03 8.1 Example 2 A 100 0 0.1 0.03 8.1 Example 3 A 100 0.1 0.1 0.03 8.1Example 4 A/B 75/25 0.1 0.1 0.03 6.1 Example 5 A1 100 0 0 0.03 — Example6 A1 100 0 0.1 0.03 — Example 7 A1 100 0.1 0.1 0.03 — Example 8 A3 100 00 0.03 — Example 9 A3 100 0 0.1 0.03 — Example 10 A3 100 0.1 0.1 0.03 —Example 11 A7 100 0 0.1 0.03 — Example 12 A8 100 0.1 0.1 0.03 — Comp.Ex. 1 B 100 0 0 0.03 — Comp. Ex. 2 B 100 0 0.1 0.03 — Comp. Ex. 3 B 1000.1 0.1 0.03 — Comp. Ex. 4 A2 100 0 0 0.03 — Comp. Ex. 5 A2 100 0 0.10.03 — Comp. Ex. 6 A2 100 0.1 0.1 0.03 — Comp. Ex. 7 A4 100 0 0 0.03 —Comp. Ex. 8 A5 100 0 0.1 0.03 — Comp. Ex. 9 A4 100 0.1 0.1 0.03 — Comp.Ex. 10 A6 100 0 0.1 0.03 — (*1) Ratio of the polymethylene-dicarboxylicacid to bisphenol A in the polycarbonate resin composition.

TABLE 2 Degree of Falling Weight Microprism Impact Luminosity Transfer(%) Strength (J) (Cd/m²) Example 1 99 43 260 Example 2 99 42 261 Example3 99 40 320 Example 4 98 41 315 Example 5 98 43 250 Example 6 98 42 257Example 7 98 40 310 Example 8 99 41 250 Example 9 99 40 256 Example 1099 41 308 Example 11 99 40 256 Example 12 99 41 308 Comparative Example1 90 40 215 Comparative Example 2 90 39 218 Comparative Example 3 90 39290 Comparative Example 4 90 40 215 Comparative Example 5 90 39 218Comparative Example 6 90 39 290 Comparative Example 7 99 11 244Comparative Example 8 99 12 248 Comparative Example 9 99 10 305Comparative Example 10 90 39 220

INDUSTRIAL APPLICABILITY

In the invention, used is a polycarbonate resin composition having highmechanical strength and having improved flowability, for the material ofoptical waveguide. Therefore, the optical waveguide made of the resincomposition enjoys good transfer of a microprism structure onto its faceor back, and has high mechanical strength and good photoconductivity.

1. An optical waveguide which comprises (A) a copolyester carbonatehaving aliphatic segment(s), the optical waveguide being made of atabular molding and having a light-scattering layer formed directly onthe face or back.
 2. The optical waveguide as claimed in claim 1,wherein the aliphatic segment in the component (A) is derived from apolymethylene-dicarboxylic acid, and the ratio of thepolymethylene-dicarboxylic acid falls between 1 and 30 mol % of the mainmonomer (diphenol) that constitutes the polycarbonate resin composition.3. The optical waveguide as claimed in claim 1, wherein thelight-scattering layer has a microprism structure.
 4. A method forproducing the optical waveguide of claim 3, in which, when a tabularmolding for it is injection-molded, a microprism structure that servesas a light-scattering layer is transferred onto its face or back with astamper.
 5. The optical waveguide as claimed in claim 3, wherein themicroprism structure is a regular tetrahedral structure.
 6. A method forproducing the optical waveguide of claim 5, in which, when a tabularmolding for it is injection-molded, a microprism structure that servesas a light-scattering layer is transferred onto its face or back with astamper.
 7. The optical waveguide as claimed in claim 5, wherein theregular tetrahedral structure has a height falling between 10 and 300μm.
 8. A method for producing the optical waveguide of claim 7, inwhich, when a tabular molding for it is injection-molded, a microprismstructure that serves as a light-scattering layer is transferred ontoits face or back with a stamper.
 9. A device, comprising: the opticalwaveguide of claim 1 and a light source.
 10. A method of scatteringlight, which comprises: illuminating a surface of the optical waveguideof claim 1 with a light and directing the light through thelight-scattering layer.
 11. An optical waveguide made from apolycarbonate resin composition that comprises (A) a copolyestercarbonate having aliphatic segment(s), and at least one resin selectedfrom (B) an aromatic polycarbonate and (C) an acrylic resin, in whichthe amount of (B) is at most up to 90 parts by weight relative to 100parts by weight of (A), and the amount of (C) falls between 0.01 and 1.0part by weight relative to 100 parts by weight of (A), the opticalwaveguide being made of a tabular molding and having a light-scatteringlayer formed directly on the face or back.
 12. The optical waveguide asclaimed in claim 11, wherein the aliphatic segment in the component (A)is derived from a polymethylene-dicarboxylic acid, and the ratio of thepolymethylene-dicarboxylic acid falls between 1 and 30 mol % of the mainmonomer (diphenol) that constitutes the polycarbonate resin composition.13. The optical waveguide as claimed in claim 11, wherein thelight-scattering layer has a microprism structure.
 14. The opticalwaveguide as claimed in claim 13, wherein the microprism structure is aregular tetrahedral structure.
 15. The optical waveguide as claimed inclaim 14, wherein the regular tetrahedral structure has a height fallingbetween 10 and 300 μm.
 16. A device, comprising: the optical waveguideof claim 11 and a light source.
 17. A method of scattering light, whichcomprises: illuminating a surface of the optical waveguide of claim 11with a light source and directing the light through the light-scatteringlayer.
 18. An optical waveguide which comprises an aromaticpolycarbonate resin terminated with a substituted phenoxy group of ageneral formula:

in which R¹ represents an alkyl group having from 10 to 30 carbon atoms,or a branched alkyl group having from 10 to 30 carbon atoms, or aformula:

or a formula

and, the optical waveguide being made of a tabular molding and having alight-scattering layer formed directly on the face or back.
 19. Theoptical waveguide as claimed in claim 18, which comprises from 0.01 to1.0 part by weight of an acrylic resin relative to 100 parts by weightof the aromatic polycarbonate resin therein.
 20. The optical waveguideas claimed in claim 18, wherein the light-scattering layer has amicroprism structure.
 21. The optical waveguide as claimed in claim 20,wherein the microprism structure is a regular tetrahedral structure. 22.The optical waveguide as claimed in claim 21, wherein the regulartetrahedral structure has a height falling between 10 and 300 μm.